Subject vs AnonymousSubject

Question

What's the difference between Subject and AnonymousSubject in RxJS 5? I've searched the internet but didn't find any info about AnonymousSubject.

I've found an example on the web

Subject.create(observer, observable);

Looking into rxjs source code I saw that this creates and AnonymousSubject. Can you also come up with an example when is good to use AnonymousSubject?

There is a use case in the RxJS4 documentation: https://github.com/Reactive-Extensions/RxJS/blob/master/doc/api/subjects/subject.md#example-1 — cartant, Feb 10 '17 at 07:52

score 9 · Accepted Answer · edited May 23 '17 at 11:47

9

The AnonymousSubject doesn't subscribe itself to the source Observable. It just connects the source and destination.

I don't know what a typical use-case for AnonymousSubject looks like but it's used inside Subject.lift().

Also see: RxJs Subject.subscribe method not working as expected

edited May 23 '17 at 11:47

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answered Feb 10 '17 at 07:49

martin

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score 1 · Answer 2 · answered Jun 12 '20 at 11:16

You can use AnonymousSubject to define an operator that returns a hot observable. Usually the Observable will be a Subject too, for example a BehaviorSubject.

On the Observer side, the onNext method will "do something" with the value it receives and push to the destination Subject. For example an the observer could accept a boolean value for "is the network connection available", try connecting to a server when the network connection becomes available, and push true to a BehaviorSubject if the attempt to connect succeeds. This AnonymousSubject would tell you upon subscription whether you are connected to the server.

Subject vs AnonymousSubject

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